Semiconductor technologies are continually progressing to smaller feature sizes, for example, down to 65 nanometers, 45 nanometers, and below. A patterned photoresist layer is used to transfer a designed pattern having small feature sizes from a photomask to a wafer. In a typical chemically amplified (CA) resist, exposing radiation releases acid from a photo-acid generator (PAG) in the CA resist to form a latent image within the resist film. Subsequently, a post exposure bake (PEB) is implemented to drive acid-catalyzed cross-linking or deprotection reactions in the resist film. To enhance resolution of fine patterning of small feature sizes, recent attempts have been made to shorten an exposure light source's wavelength and elevate a projector lens's numerical aperture (in other words, the projector lens has a high numerical aperture). To further elevate the resolution, extreme ultraviolet lithography (EUVL) has been proposed. However, EUVL may suffer out-gassing contamination during higher energy exposing processes, thus leading to contaminated lenses.
Therefore, there is need for a photoresist material and a lithography method to address the above issue.